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Relay problem?


JoeR

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So occasionally when I am driving, I hear a clicking sound coming from under the passenger side dash near the door, and a couple seconds after that, the engine will loose power and die. I know that both the auto choke relay as well as the fuel pump control unit are located there. Would these be the problem? Has anyone else had this problem?

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If there is a problem with the alternator charge the choke heater relay will buzz sometimes. But this won't cause the engine to quit. The fuel pump relay on the other hand has to be working to keep the pump... pumping. In operation, turning the key to ON will turn the relay on and start the fuel pump but there is a timer of 20-30 seconds? and will then shut off. Turning the key to START will also turn the relay on and as long as you are cranking the pump will operate but when the key is released the timer begins again. The relay will stay on only if there is oil pressure and charge from the alternator which it is assumed the motor has started and is running.

 

Why the pump relay? Well after an accident, do you really want the pump to continue supplying gas to a broken fuel line or carburetor untill the tank is empty while you lay there unconscious?

 

If you suspect a faulty relay forget the manuals, many don't even mention it. I did find this very helpful site for fixing it yourself and saving $50.

 

http://dlarson.hubpages.com/hub/The-Datsun-and-Nissan-Pickup-Fuel-Pump-Relay-What-the-Haynes-Automotive-Repair-Manual-Wont-Tell-You.

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Thanks for the link to that article, I will be checking that out in the next few days. It's funny how the Haynes manual doesn't mention the fuel pump relay. I have a Chilton manual and it doesn't show anything about a fuel pump relay either. But I I have one more question: can the problem be exacerbated by there being more fuel in the tank? I seem to only have the problem when the tank is more that half full.

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2238132_f248.jpg

 

Well if you disconnect the plug from the relay and make a jumper wire from the White (ignition) to the White/Black (pump) the pump should only run when the key is in the ON position. If it runs without quitting, then the relay or one of the other inputs is bad causing it to shut off. If the pump still acts up then it could be the pump as you've eliminated the relay by jumpering around it..

 

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Do the standard fuel pump 1) Volume and 2) Pressure tests. The pressure and volume and similar for all Datsuns.

 

Note that the 720 electric fuel pumps have filters inside the pump. If they never been changed, it can affect the volume and the pressure. New filters are available from Nissan.

 

The pump is just in front the rear left wheel on the frame.

 

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